1. Field of the Invention
The present invention deals with the field of devices which improve airflow over sailcraft mainsails, boom jibs, and/or mizzen sails in such a manner as to improve the driving force and reduce the resistance force thereof.
A sail is much like an airplane wing in that it generates driving force responsive to a difference in air velocities as the air flows over the curved surfaces thereof. In this manner, air pressure differential is generated by virtue of velocity acceleration being higher on the leeward side than on the windward side. This results in a problem being created at the ends of the sails where the air tends to flow from the high pressure side to the low pressure side. Such cross flow reduces the difference in pressures and thus reduces driving force.
A circular airflow pattern or vortex can be created in this manner which tends to rob energy from the air velocity and hence increase the sail resistance force. The present invention provides a novel means for minimizing the airflow circulation from the high pressure side to the low pressure side of a sail.
2. Description of the Prior Art
Devices for overcoming these types of problems are many and varied in the prior art such as those shown in U.S. Pat. No. 3,820,493 issued June 28, 1974 to James L. Amick for Sailboat Improvements; U.S. Pat. No. 4,280,431 issued July 28, 1981 to Morris B. Sofen for a Device For Supporting And Storing The Mainsail Of A Sailboat On The Boom Thereof; U.S. Pat. No. 4,347,799 issued September 1982 to Vincent C. Moriarty for a Sail Catcher; U.S. Pat. No. 4,354,444 issued Oct. 19, 1982 to Mario J. Puretic for a Sail Handling Apparatus; U.S. Pat. No. 4,432,298 issued Feb. 21, 1984 to Patrick J. Cudmore for a Hydrofoil Sailing Craft; U.S. Pat. No. 4,745,871 issued May 24, 1988 to Edwin F. Wieder for a Method And Apparatus For Covering And Containing A Sail; French Pat. No. 2543509 issued October, 1984; French Pat. No. 2552393 issued September, 1983; Japenese Pat. No. 57-167894 issued October, 1982; Japenese Pat. No. 57-84295 issued May, 1982; German Patent No. 3342911 issued June, 1985 and PCT Pat. No. 79/01077 issued December, 1979.